Low-melting-point substances, for example, wax-like substances, glycerine fatty acid esters, etc., are used in fields such as sustained-release preparations and preparations for masking bitterness.
For example, the specification of Japanese patent No. 3130058 discloses granules obtained by melt-granulating a powdered or granular water-insoluble low-melting-point substance, a powdered or granular disintegrator and a powdered drug having an unpleasant taste, and melting the thus obtained granules at a temperature not less than the melting point of the low-melting-point substance with a fine powder additive under flow conditions. The fine powder additives disclosed in the above-mentioned patent specification include talc, light anhydrous silicic acid, magnesium metasilicate aluminate, calcium stearate, magnesium stearate, titanium oxide, synthetic aluminum silicate, etc.
Specification of Japanese patent No. 2915653 discloses granules obtained by melt-granulating a powdered or granular drug having bitterness and a powdered or granular water-insoluble polymer selected from the group consisting of acrylic polymers, cellulose-based polymers, and their mixture, with a powdered or granular water-soluble low-melting-point substance having a melting point of 40-90° C.
However, the granules disclosed in these patent specifications are prepared so as to mask the unpleasant taste of a drug with the drug being immediately released. The granules disclosed in these patent specifications are fast released and do not have sustained-release properties.
Regarding sustained-release preparations, Japanese Unexamined Patent Publication No. 2001-278781 discloses a sustained-release preparation and a preparation method thereof, wherein a drug-containing core material having a particle diameter of not greater than 200 μm is spray-coated with a liquid obtained by dissolving a mixture of a hydrophobic organic compound and a water soluble polymer in an organic solvent, and the spray-coated layer is further spray-coated with a different liquid obtained by dissolving a mixture of a hydrophobic organic compound and a water soluble polymer in an organic solvent.
Because the method disclosed in Japanese Unexamined Patent Publication No. 2001-278781 employs spray coating, the use of an alcohol, ketone, halogenated hydrocarbon, ester, ether or like organic solvent is crucial. Use of such organic solvents adversely affects the human body, etc., both during the production of such preparations and when administered.